A blood vessel prosthesis has been proposed which is obtained by culturing smooth muscle cells using a porous scaffold material composed of a thermoplastic resin (see Patent Document 1). The blood vessel prosthesis is obtained by forming the scaffold material into a tube of thickness about 2 mm, filling the inside of the scaffold material with a collagen solution containing smooth muscle cells, and culturing the smooth muscle cells in the scaffold material in an incubator at 37° C. for about three days. In the blood vessel prosthesis, since the scaffold material is porous, the smooth muscle cells are distributed into the tube wall of the scaffold material without becoming necrotic.    Patent Document 1: Japanese Patent Publication No. 2003-284767